A tiny shell (7 mm length) of a juvenile Mollusc (supposed gastropod) was discovered enclosed within the packstone filled shell of a terebratellidine brachiopod (Zittelina hofmanni Bujtor and Vörös, 2020) from the Lower Cretaceous Apátvarasd Limestone Formation of Zengővárkony (Mecsek Mountains, South Hungary). Serial sectioning of the brachiopod shell revealed that in addition to the brachidium, a different and unusual shelly structure was preserved inside the brachiopod shell. 2D serial sections were digitalized and fed into Free-D imaging software to generate a 3D reconstruction of the entombed fossil, which is supposed a juvenile gastropod. Consideration of the emplacement, dimensions, and orientation of the shell suggests that it entered the cavity of the living brachiopod shell as an egg or larva and was trapped. Further analysis of both fossils suggests that the two animals lived and developed beside each other for a longer period: the brachiopod crus is less developed and slightly deformed on the gastropod side with the gastropod placed parallel to the crura and the lateral wall of the brachiopod. This example suggests that shells of brachiopods may have provided sheltered microhabitats for benthic micro- and macrofossils not only after the death but even during the life of the host brachiopod. This is the first evidence from the fossil record for the co-existence of a living Mollusc inside the shell of a living brachiopod. This work illustrates how general purpose 3D modelling software initially developed in other disciplines may provide new insights in the wide field of geosciences.
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No competing interests reported.
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Posted 24 Mar, 2021
On 08 Apr, 2021
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On 31 Mar, 2021
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Posted 24 Mar, 2021
On 08 Apr, 2021
On 08 Apr, 2021
On 08 Apr, 2021
Invitations sent on 08 Apr, 2021
On 31 Mar, 2021
On 22 Mar, 2021
On 22 Mar, 2021
On 17 Feb, 2021
A tiny shell (7 mm length) of a juvenile Mollusc (supposed gastropod) was discovered enclosed within the packstone filled shell of a terebratellidine brachiopod (Zittelina hofmanni Bujtor and Vörös, 2020) from the Lower Cretaceous Apátvarasd Limestone Formation of Zengővárkony (Mecsek Mountains, South Hungary). Serial sectioning of the brachiopod shell revealed that in addition to the brachidium, a different and unusual shelly structure was preserved inside the brachiopod shell. 2D serial sections were digitalized and fed into Free-D imaging software to generate a 3D reconstruction of the entombed fossil, which is supposed a juvenile gastropod. Consideration of the emplacement, dimensions, and orientation of the shell suggests that it entered the cavity of the living brachiopod shell as an egg or larva and was trapped. Further analysis of both fossils suggests that the two animals lived and developed beside each other for a longer period: the brachiopod crus is less developed and slightly deformed on the gastropod side with the gastropod placed parallel to the crura and the lateral wall of the brachiopod. This example suggests that shells of brachiopods may have provided sheltered microhabitats for benthic micro- and macrofossils not only after the death but even during the life of the host brachiopod. This is the first evidence from the fossil record for the co-existence of a living Mollusc inside the shell of a living brachiopod. This work illustrates how general purpose 3D modelling software initially developed in other disciplines may provide new insights in the wide field of geosciences.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
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